Add Xfermode bench. Also clear before rendering in bench (rather than after).

include/core/SkXfermode.h

 
 /*
  * Copyright 2006 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 
 #ifndef SkXfermode_DEFINED
@@ skipping 110 matching lines @@
         kExclusion_Mode,
         kMultiply_Mode,
 
         kHue_Mode,
         kSaturation_Mode,
         kColor_Mode,
         kLuminosity_Mode,
 
         kLastMode = kLuminosity_Mode
     };
+    
+    /**
+     * Gets the name of the Mode as a string.
+     */
+    static const char* ModeName(Mode);
 
     /**
      *  If the xfermode is one of the modes in the Mode enum, then asMode()
      *  returns true and sets (if not null) mode accordingly. Otherwise it
      *  returns false and ignores the mode parameter.
      */
     virtual bool asMode(Mode* mode) const;
 
     /**
      *  The same as calling xfermode->asMode(mode), except that this also checks
@@ skipping 121 matching lines @@
         fProc = proc;
     }
 
 private:
     SkXfermodeProc  fProc;
 
     typedef SkXfermode INHERITED;
 };
 
 #endif